The study of quasars and the systems around them is one
method of exploring how galaxies are formed and the overall
large-scale structure of matter in the universe. Ultraviolet
Hubble Space Telescope spectra taken toward the z=0.223
quasar PKS0312-770 have revealed intergalactic absorption
lines at redshifts of z=0.2028, z=0.1983, z=1589, and
z=0.1575. The purpose of this research was to measure the
redshifts of a large number of galaxies in the sightline
towards this quasar to search for clusters or groups of
galaxies which are responsible for producing absorption
lines at these specific redshifts. Redshifts were measured
using data from 132 spectra that were taken with the Wide
Field Reimaging CCD Camera on the 2.5 m Irènèe du Pont
telescope at Las Campanas Observatory on October 30 through
November 3, 2002. We detect an excess of galaxies at
redshifts of z=0.15, z=0.19, and z=0.20 which may be
responsible for the absorption line systems seen in the HST
data and we identify probable galaxies associated with these
intervening absorbers. We also identify an excess of
galaxies near z=0.05 which may indicate a nearby cluster
of galaxies which does not produce an absorption signature
in the quasar's spectrum.

The author(s) of this abstract have provided an email address
for comments about the abstract:
giandoni@nmsu.edu